The error, Failure in Loader: VerifyError: Error #1014″, within the Composite Application Framework (Mosaic) can be caused by the presence of a non-interface class within the interface library that defines a service within Mosaic. Service interfaces should not use non-interface classes as arguments or results. For example, if a service that is being implemented returns an ArrayCollection, the result should be specified in the interface as IList. Creating an interface with an ArrayCollection in its definition will cause other tiles to throw this exception.